1. Field of the Invention
The present invention generally relates to ball valves and, more particularly, toward handle stops for ball valves.
2. Description of Related Art
Two types of valves are used in the marine industry. The first type is known as a “seacock”, having its top port threaded for a National Pipe Tapered Threads Standard (NPT) connection and its bottom port flanged and threaded for a National Pipe Straight Threads Standard (NPS) connection, and are generally used in engine cooling systems or any system that passes water between the outside of the vessel and the inside of the vessel. The second type of valve is known as an “in-line” valve having NPT threaded ports at each end, and generally used for on-board plumbing systems. In marine vessels, plumbing systems for fuel supply and for various on-board systems are generally equipped with “in-line” ball valves. Engine cooling systems are generally equipped with “seacocks”.
With reference to FIGS. 10a–10b, because there are two or more engines 100a, 100b in many marine vessels, plumbing systems 101a, 101b are dedicated to each engine and duplicated for the same purpose on each other engine. Access to the vessel engine room is generally on the vessel centerline, between the engines 100a, 100b. Once in the engine room, one who wishes to operate any of the valves therein must look left to operate the valves 102a, 104a of the one plumbing system 101a in the port (left) side of the vessel, and then look right to operate the valves 102b, 104b of the second plumbing system 101b in the starboard (right) side of the vessel.
With both types of valves, assuming the valves 102a, 104a on the port (left) side of the vessel are installed so as to have their handle facing inboard when in the closed position, the corresponding valve 102b, 104b that serves the same purpose on the starboard (right) side of the vessel would have its handle facing outboard when in the closed position. This situation is shown in FIG. 10b. Or, the starboard valve could be oriented so as to have its handle facing outboard when closed, but the direction of handle rotation would be the opposite of the valve on the port side. Neither option is desirable, as it is visually confusing, which could result in valve damage if the operator were to force the valve handle in a wrong, but logical direction. With seacocks, the latter option is not possible due to the different threading and mounting details on opposite ends of the valve.
It is desirable to have all valves, regardless of their type or which side of the vessel they are installed on to have their handles in the same relative position (inboard or outboard) when in the closed position, as this makes valve operation more convenient and more logical. Selectively changeable handle rotation direction is particularly useful for seacocks, as this type valve cannot be selectively installed (end for end).